If you accept the quest Sarah will open the gates to the 5 pens in the area, one at a time. Watch her, as she will run into the pens she opens and aggro the mobs inside.

The first pen contains crebain, the second dwarf and man prisoners, the third orcs and wargs, the fourth elven prisoners, and the 5th orcs and wargs.

Make sure that when the tank has mobs they face away from Sarah Oakheart, otherwise their frontal AoE will kill her.

Once the elven prisoners are released 3 orcs will spawn in the path towards the entrance. There is no penalty for allowing the prisoners to die, so make sure you are first watching Sara as she opens the last pen, and only then saving the elven prisoners. Sara must be kept alive or her quest will fail.

Once these mobs are dead, Sara will run towards the entrance, where you will confront the two uruks Shiruk and Kamordî. These uruks both do full AoE damage, so ranged dps works best.